"International crude oil prices fluctuated at a high level in the first half of the year and plunged in the second half with a precipitous drop in the fourth quarter," the company said.

The Chinese government cut its state-set prices for oil products 11 times in the second half of 2014 as international crude prices plummeted, it said.

The company's revenue slipped 1.9 per cent to 2.83 trillion yuan in 2014, according to the statement.

Sinopec also issued a profit warning for the first quarter of this year, as international oil prices are expected to remain weak.

"The price of international crude oil has declined significantly since the fourth quarter of 2014 and still remained at a low level in the first quarter of 2015," it said in a separate statement.

By early afternoon on Monday, Sinopec was down 0.16 per cent in Shanghai and 2.74 per cent lower in Hong Kong.

In the annual report for 2014, Sinopec made no mention of media reports that the government plans to merge it with another domestic energy behemoth, China National Petroleum Corp (CNPC). It has previously denied the rumours.

China is planning structural reforms to the energy sector this year, the official Xinhua news agency reported in February, quoting an industry official as saying: "The reform plan will have significant impact on the current oil and gas system."